This invention relates to apparatus for use in operator training with, and the testing and evaluation of, infrared sensors for missile detection. More especially, this invention relates to apparatus for use in the testing and evaluation of infrared sensors which are for missile detection and which integrate incident energy over a finite time period.
Apparatus is known for use in operator training with, and the testing and evaluation of, infrared sensors for missile detection. The known apparatus comprises an infrared illumination source for illuminating the sensors. The infrared illumination source may be a lamp such for example as a xenon arc lamp or a quartz halogen lamp. Alternatively, the infrared illumination source may be thin filaments of carbon or a metal. The apparatus tests and evaluates the infrared missile detection sensors by illuminating them. The infrared missile detection sensors may be positioned on, for example, an aircraft.
In the above mentioned known apparatus, the use of infrared illumination sources such for example as the lamps or the thin filaments has proved to be a limiting factor in the generation of high powers in the mid-infrared wavelength range of 3-5 μm. More specifically, problems associated with the known apparatus using the lamps or the thin filaments are as follows.    1. High input power requirements for high power sources.    2. Attempts to reduce out of band wavelengths may lead to thermal management issues.    3. The generation of wavelengths which extend beyond the required infrared band can result in impractical operating conditions due to the wavelengths generated, such impractical operating conditions including those relating to eye safety and to covertness of source.    4. The beam width in any illumination system is limited by the source extent and by aperture constraints. For complete coverage of all infrared missile warning sensors, for example as placed on an aircraft, a beam width around 3° is required. However, beam widths much greater than 3° obtained with existing infrared illumination sources may result in a lower power density across the intended target.    5. Modulation capabilities of heated lamps and filaments are limited. These modulation capabilities are adequate for present day infrared missile detection sensors but they generally do not have the capacity for future developed infrared missile detection sensors.    6. High electromagnetic emissions, which are related to normal operation and the infrared illumination source being modulated, may be generated at problematic magnitudes. This is especially a problem for infrared illumination sources in the form of lamps.    7. The known infrared illumination sources cannot generate sufficient infrared power within aperture limitations which apply. These aperture limitations are dictated by the need to present a realistic source extent to the sensor, for example when mounted on an aircraft. This is especially so where imaging systems are employed.
It is an aim of the present invention to reduce the above mentioned problems.